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Air Fork?

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Kawasaki already took a page from MTB forks by putting the spring in one leg and the damper in the other. Now it looks like they're using an air spring. It would be nice to shave a couple pounds off my front end by ditching one damper and two coil springs.

Showa1.jpg

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Showa has provided forks for Trials bikes since the late nineties with the spring in one leg (with a preload adjuster) and a cartridge in the other (with compression and rebound clickers).

Air springs were a fad for a short time back in the seventies. I did the conversion on two bikes but the air springs are high maintenance and a PITA; OK if you have a mechanic to fuss with the bike between motos. Honda also had guidance in some manuals in the early eighties on using air pressure as a supplement spring.

I think the best is a spring and then tune with oil level, which is changing the compression ratio for an air spring. Using air pressure instead of a spring makes getting rider sag a PITA. Maybe it is easier now with the more accurate pressure gauges, but IMO a high maintenance solution with little benefit for most riders.

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In the mtb world they've mastered sealing and rate curves on air springs. Now it's just a matter of preference. Some choose air to save weight and fine tune spring rate easily. Some choose coil for slightly less stiction and not having to check air pressures.

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Oh Contrair, twas not a fad. In the 70's everyone was drilling holes in their fork caps, tapping them and screwing schrader valves into them. The brave ones took the steel springs out. All the MX racers were using air. It was amazing that the stock seals didn't usually fly up and deflate the forks. Fox made air shocks for the factory Honda bikes. As a matter of fact, when I got out of racing in the early 80's air forks were still in use. What happened? I feel like the guy who fell into a glacier and thawed out 35 years later. Why did the industry move away from air suspension in the first place? It saves a pound and a half of unsprung weight and is infinately more adjustable than springs. Mountain bikes use nothing but air suspension unless you are talking about a downhill bike. I never see springs on a Mtn bike in the Dallas area (no mountains) I hope all the MX bikes go to air again. It causes issues with stiction but there are ways around it like isolating the air spring. I've got a fox RP3 air shock on my mountain bike and I haven't had to add air to it in a year. I don't ride it that much but the shock works great with excellent damping and a progressive spring rate. I don't know if they will ever get air springs to be as progressive as metal but they are close.

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Being a downhill mountain biker and very new to the sport of dirt biking, I am very excited to see what will happen with the air forks coming out from honda and kawasaki. I love the progressive feel of air in the forks and as long as they just keep it to the forks I think it will probably work great, I do think its a little funny that they only pump these ones up to 30-40 psi when a mtn bike runs much higher pressure. At the same time I dont think i would like a dirt bike with an air shock on it. I have never liked the air shocks on mountain bikes and I dont think it would ever work in a larger scale. I am all for the air forks as long as I can keep a boinger on my shock I will be happy haha.

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I kind of agree with chuck. Dirt bikes are used in a variety of temperatures, and checking your air pressure would add to the list of pre ride stuff. Tuning would be a bear as well with barometric pressure, humidity and temp changes all affecting the density and pressure of the air inside the fork. Also, what happens if a fork suddenly loses pressure? In a coil spring fork if the spring broke the spring would still be there.

I haven't looked too closely at the designs, but contrary to what I said it seems like a nice design.

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riding in big elevation gain areas must also affect the air forks? of course if it is only on an MX bike not a problem.

Joe

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I haven't ridden a new enough bike to have the seperate damper/spring setup. I can see it working well on mtbs and minis like the 65SX (my brother had one so I know it works well on them) but on a bigger, heavier bike I would think the extra weight and force would create some bindage in the forks. I guess it either doesn't or it's negligible though since they're still doing it but I'm still skeptical.

Edited by Ih8Hondas
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Barometric pressure won't affect air suspension because it is a closed system. I've never noticed the temperature affecting it either. Temperature affects the oil more than the air in a suspension anyway. As far as air not being able to handle the extra force, huge trucks use air suspension. It's all hydraulics. Some Mountain bike suspensions use oil for damping and some use air only. The Fox RP3 on my mtn bike works great for damping and spring progression in all temperatures. Most downhillers opt for steel or ti sprung rear ends because they have much more travel than the cross country bikes and weight is not as much of an issue. and the steel spring just feels more progressive than air. The factory honda team used air shocks on their dual shock models back in the 70's. I guess when the technology went to the single shock cantilever design nobody bothered to build an air shock for it. But if they are putting air in the forks now it's just a matter of time till they do a shock too.

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The main problem with air suspension I remember from the past is.. When it fails, it's like a tire going flat. No fork oil dribble warning.. Just, pssss, and it's flat. Then it's a major rebuild to get it back.

I've got a Fatty air fork on my Cannondale Mtn bike, and so far, so good. But, I haven't rode it all that much, plus it's a considerable difference from a KX450.

Sounds like a good idea at first glance, but we'll see how much wailing and gnashing of teeth there is down in the KX450 forum after a year or so (My POS air fork is leaking after only 3 months, and the dealer says it will cost $500 to fix, what do I do? Please help! :devil: )..

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I'm also an old geezer who can remember the air fork fad of the 70's. I didn't do it on my bikes, but I did help install it on others. Like others have said, back then it was a real hassle. I hope the new technology is better, because in principle and air spring has some major advantages.

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When air suspension came out for mountain bikes, the forums (yes there was internet back then) were all grumbling about not wanting to be stuck out in the middle of nowhere with a flat suspension. That was at least 15 years ago. I bought an air shock and went ten years without it going flat once. When the shaft got nicked and the seals got old it started leaking and eventually wouldn't hold air. But the worst that happend was having to limp back to the car with the rear end dragging. The air forks have been just as good. Only had a couple problems in 15 years. I wish someone could enlighten us on why the factories went away from air in the 80s. I have no doubt that the technology can be made to work. In formula 1, they use air for the valve springs. The engines basically reached the point where they could rev higher than the metal valve springs could handle. If air can be used for valve springs it can surely be used for a motorcycle suspension.

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